Apparatus and process for sorting solid particle material in a fluidized liquid medium



Jan. 29, 1963 M. DELACHANAL 3,075,643

APPARATUS AND PROCESS FOR SORTING SOLID PARTICLE MATERIAL IN A FLUIDIZED LIQUID MEDIUM Filed May 8, 1961 2 Sheets-Sheet 1 IN VEN TOR, /W/cwa fm CHA/m TTORNEV Jam 29, 1963 M. DELACHANAL 3,075,643

APPARATUS AND PROCESS FOR SORTING SOLID PARTICLE MATERIAL IN A FLUIDIZED LIQUID MEDIUM Filed May 8, 1961 2 Sheets-Shoot 2 A NORA/5% 3,@75d3 Patented Jan. 29, 1953 APPARATUS AND PROCESS FR SRTING SLlD PARTECLE MATERHAL EN A FLUIDIZED LlQUlD MEDlUlt/ Michel Deiachanal, Grenoble, France, assigner to Societe Grenobloise dEtudes et dAppiications Hydrauliques, Grenoble, France, a corporation ot France, and Cornrnissariat a lEnergie Atomique, Paris, France Filed May 8, 196i, Ser. No. 103,374 Claims priority, application France May 10, 1960 i7 Claims. (Cl. 209-153) The present invention relates to the son-ting of grains or particles of solid material in mixtures thereof and has for its primary purpose the provision of 4an improved method of and apparatus for per-forming such operation.

The problem of sorting the particles in mixtures by density or grain size frequently arises and a number of different types of devices have been provided to accomplish such purpose. Some of these devices are constructed to utilize the phenomenon known as uidization. It is known that if a mixture of two ingredients in a solid particle material to be separated, is placed in a tube, and a liquid is then made to flow through the tube at suc-h a velocity that the mixture is expanded sufliciently to enable relative movement to occur between the grains thereof-that is to say, a fluidized condition is reached the ingredients of the mixture after a certain time undergo a sorting process and if the proper velocity conditions are present, one of the ingredients will collect at the upper end of the tube, and the other ingredient will collect at its lower end, while a mixture of the two ingredients will be present in an intermediate zone between the two ends of the tube.

The principal object of the present invention is to provide a commercially practical process utilizing the phenomenon of fluidizationand capable'of lautomatically and continuously sorting mixtures of solid particles.

In accordance with the invention, there is provided an apparatus having two vertically disposed compartments, one of which is enclosed by the other compartment and is separated from the latter by a suitable partition. The bottom end portions of the two compartments are in communication with each other and the bottom ends of yboth compartments are `defined by a common floor consisting of a screen through which the sorting liquid flows in the practice of the invention. The materials to be sorted by the liquids are introduced into the outer of the two compartments and the sorting process takes place in the latter; one of the sorted ingredients orf the materials remaining in such outer compartment and the other sorted ingredients moving toward and into the bottom end portion of the other compartment. Each of the compartments is provided with means for discharging the sorted ingredients contained therein.

in the use of the aforesaid apparatus, the sorting liquid, as has been indicated, is fed through the screen at the bottom of the compartments in such manner as to produce in both compartments a permanent fluidized state such as to cause a relative movement between the particles of solid material therein that will result in their classification. In order that such classification of the ingredients o-f a mixture is effected as an automatically controlled continuing operation, the materials in the outer co partment yare maintained at a higher level than the materials in the other compartment, the difference between the two levels being preferably such that the apparent weight of a column of the fluidized material having a unitary cross-sectional area in one compartment, is the same as the apparent weight of a column of the ilu-idized material having the same Vunitary cross-sectional area in the other compartment. It is to be noted at this time that where further reference is made in the specication and claims to the apparent weight per unit crosssectional area of a material, it shall be understood that what is meant is the apparent weight of a column of the fluid-ized Imaterial in a compartment and having a unitary cross-sectional tarea.

Under the aforesaid conditions, there will occur in the region of the outer compartment into which are fed the materials to be sorted, a mixture of such materials and liquid such as to cause the sorting process to take place. This region or zone is intermediate the upper and lower ends of the outer compartment and is preferably situated at about midway of the total height of such compartment. As a result of the sorting process taking place in this zone, one of the ingredients released from the particle material moves towards the top of the outer compartment where it is discharged through an outlet provided for that purpose, and the other ingredients collect near the bottom of the outer compartment, from whence they iind their way into the inner compartment through the passage provided at the bottom of the partition. After entering the inner compartment, the other ingredients are conveyed by the liquid toward the top thereof and then discharge-d through an outlet provided at the top of the inner compartment for that purpose.

In most cases, the heavy or coarse grains of the solid Amaterial collect in the inner compartment and discharge from the apparatus at the lowest outlet level, whereas the light or line particles of suoli material rise in the outer compartment and are discharged therefrom at the highest outlet level of the apparatus. This is because there is provided in accordance with the invention, a velocity of dow of the liquid at its entry into the two compartments substantially equal to the velocity of fluidization of the heavy or coarse ingredients of the mixture so that the light or fine particles are `subjected to a greater ow velocity than their minimum tluidization velocity and thereby are cau-sed to collect at the top part of the outer sorting compartment. It will be understood in this connection that the velocity olf 'uidization for different grain sizes decreases with grain density and/or size so that the minimum iluidization velocity for the light or fine particles in a solid mixture will be much less than the minimum fluidization velocity for the heavy or coarse particles thereof.

T-he aforesaid condition should usually prevail in maintaining a stable operation -of the apparatus. In accordance with 'the invention, the liquid in the apparatus extends above the upper ends `of the two compartments to a given height, Consequently, the head of liquid above vthe screen at the bottom of the compartments has the same value in both lof the compartments. It is known that when a material is fluidized, the same laws apply as in the case of a complete liquid. However, it is also Vknown that the porosity, or voids ratio, in a fluidized material, and hence the degree of expansion of such material, vary considerably, depending on the liquid flow velocity. Therefore, when the light yor fine particles are subjected to a greater iiow velocity than their minimum fluidization velocity, as aforesaid, the resulting fluidized bed consisting of the light or fine particles in the upper portion of the sorting or outer compartment, will be expanded 'to 'a greater extent than the other iluidized beds in which the disparagement of liquid ilo-w velocity and velocity of uidization is not so great and which mainly consist of the grain mixtures in the intermediate sorting Zone, and the heavy or coarse grains at the bottom of the outer yor sorting compartment and in the whole of the inner compartment. lf, therefore, the fluidized bed of light lines were not at a higher level than the bed of the heavier fines, but the two beds were at the same level `paratus would be inoperative.

in both compartments, the apparent weight per unit crosssectional area of the materials in the outer sorting compartment would be less than that of the material in the inner compartment, with the result that the columns in the two compartments would be unbalanced and the ap- Hence in accordance with the invention, it is important, usually that the materials in the outer sorting compartment be kept at a higher level than the materials in the inner compartment in order to achieve the state of equilibrium between the two iluid oolumns'on which the stable operation of the apparatus depends.

It will be understood, however, that in certain cases the relationships governing the apparent density variations of the two lluidized materials in a liquid medium `may be such that the light materials will discharge from the inner compartment at the lowest outlet level and that the heavy materials will discharge from the outer compartment at the highest outlet level. This is due to the fact that in spite of being heavier than other materials, certain materials have a lower apparent density than such other materials when in a uidized condition. Thus, for instance, sand has a specific gravity of 2.8 and a bulk density when iluidized of 1.5, whereas calcined alumina, -a heavier material with a speciiic gravity of 3.8, only has an apparent density of 1.0 when iiuidized.

As has lbeen above indicated, the process of the inetant invention is a continuous one and once the operaftion thereof has been initiated under the proper conditions it will automatically control itself to maintain such continuous operation. This automatic con-trol functions as follows. Any tendency of the intermediate sorting zone to rise within the outer sorting compartment indica-tes that there is a shortage of low apparent density iluidized materials and an increase in the proportion of heavier apparent density fluidized materials.

That is to say that the apparent weight per unit cross-sectional area of the column of materials contained within the outer compartment is increasing. Under such conditions, the

.process will operate automatically to cause more of the heavier or coarsegrains to be transferred from the lower `portion of the outer compartment through the passage at `the bottom of the partition and into the inner compartmen so that there is an increased discharge of the heavier grains at the upper outlet end of the inner compartment.

As a result, the intermediate sorting zone, which was Vtending to rise, will assume a lower position 'and tend ,parent density fluidized materials in the outer compartment lare on |the increase.

Under such conditions, the process will automatically correct itself by causing fewer of the heavy grains in the lower part of the outer compartment to be transferred into the inner compartment, with the vresul-t that an increased quantity of the lighter grains will be discharged through the outlet at the top of the outer compartment. When this occurs the intermediate sorting zone will tend to rise and return to its equilibrium position.

It will be understood, that in order to accomplish the aforesaid results, it is essential that the difference in the material levels in the two compartments be established sothat the apparent weight per unit cross-sectional area -is the same in both compartments. As has been indicated, this difference is achieved by suitable positioning of the outlets for the ingredients being sorted. By relating this difference'in levels in the two compartments to the apparent weights of the columns of materials therein, there Iis established Ia balanced condition which `governs the automatic regulation of the process and thereby enables the apparatus to operate continuously without permanent supervision.

lt is contemplated that several units of `the type above indicated may be arranged in cascade toprovide means for sorting mixtures consisting of more than two materials of different density or grain size.

In order that a more complete understanding of the invention may be obtained attention is directed to the following description that `sets forth by way of example an industrial design which is particularly suitable for practicing the process of the present invention to sort materials by density so that the lighter material is discharged via an outer compartment, and the heavier material via an inner compartment, and which is illustrated in the accompanying drawings, in which:

FIG. 1 is a diagrammatic sectional view taken along the vertical center of a sorting device designed in accordance with the present invention; and

FIG. 2 is Ia perspective View in elevation of the device indicated in FIG. l and partly broken away to show more clearly certain of the interior details of construction thereof.

As is shown in FIGS. l and 2, the apparatus of this invention is constructed to provide two cylindrical compartments `l and 2 separated by a partition 3 and with a common floor 4. The lower portions of the two compartments 1 and 2 `are in communication immediately above the floor at 5 by way of an annular orifice, and

Ysubstantially above the ylevel h2 defined by the top edge of the inner 'cylinder 3. The upper portion of the outer `compartrrrerit l1 is dened by the upper portion of cylinder 10 and a hollow vertical cylinder 11 disposed in axial alignment above inner cylinder 3 and having an enlarged lower end 12 enc-losing'the upper end of cylinder 3. -A

partition 13 between the enclosing end 12 of cylinder 11 and the enclosed upper end of cylinder 3 separates the outer compartment 1 -from the upper end of the inner compartment 2. The upper projecting end of cylinder 11 and lthe vupper end of cylinder 10 are enclosed by a cylindrically-shaped housing or shell member 21 which forms the Itop of the apparatus. The lower end of housing `merriberZl is closed by a partition 22 `between such member and the upper end of cylinder 10.

The material to be sorted, consisting for example of two ingredients M1 (heavy) and M2 (light), is fed into the outer compartment 1 by way of the intakes 8.

The sorting fluid, water `in this example, is fed in at the inlet 7 in the direction shown by arrow f, passes in a chamberformed by the conically-shaped wall 9 and up through the floor 4 which is in the form of a screen. After passing through the screen floor, the water flow divides into two practically equal velocity ows which feed through the compartments 1 and 2. A portion of the water ow emerging from the upper ends of the cornpartments enters both directly `from .the cylinder 10 and through the cylinder 11, into a chamber 15 formed in the shell member 21 at the upper end of the apparatus and is discharged over a weir D which is formed in such shell member 21 and which maintains a constant level in the unit. The liquid spilling over the weir D is discharged from the apparatus through an outlet pipe 16.

The value of the waterllow supplied to the underside of the screen 4 is such that the velocities of the flows passing through the compartments are slightly above the minimum fluidization velocity for the heavy ingredient M1. Consequently, these flows are higher than the uidization velocity for the lighter ingredient M2 without, however, exceeding an acceptable upper limit. By providing a Velocity of flow as indicated, both of the ingr'edients of the material either in mixture form, or in '11 and passfrom sortedbeds thereof in the two compartments, will be maintained in a state of lu-idization and expansion such as to allow relative movement to occur between the grains.

Under the aforesaid conditions of tlow, an intermediate sorting zone containing a mixture of the two ingredients M1 and M2 of the material to be sorted is formed in compartment 1 near the material feed approximately in the region indicated by the two dotted lines designated it-14. From this intermediate zone in which relative movement of the grains occurs, the lighter particles M2 sorted out of the mixture rise to the top of compartment 1 and spill over the Weir D1 formed by the upper edge of cylinder 10. The discharged particles M2 are collected in an annular chamber 17 formed between the upper end of cylinder and the upper shell member 21 and are removed from the apparatus through the discharge pipes 18. r)The heavier particles M1 separated from the mixture fall down from the intermediate zone and collect at the bottom of compartment 1. As the Water flow passes up through the compartment 2, heavy particles M1 are drawn from the bottom of compartment 1 and through the passage 5 and are caused to rise in the compartment 2 until they are iinally discharged over the spill or Weir D2 formed by the upper edge of the cylinder or partition 3. The particles M1 spilling over the weit` D2 are collected in the annular space 19 between the upper end of the cylinder 3 and the enlarged lower end 12 of cylinder such space through the discharge pipes 20.'

yIt will be noted from the foregoing that compartment 1, which may be termed the sorting compartment, contains both ingredients of the mixture; the lighter of the two ingredients forming a bed at the top of such compa-rtment, a mixture of such ingredients being locatedin an intermediate mixing zone approximately half way up the compartment, andthe heavier ingredient M1 forming a bed at the bottom of the compartment. Compartment 2, on the other hand, contains only the heavy ingredient M1. It will be noted also that the level h1 of the materials in'compartment 1 is higher than level h2 of the materials in compartment 2. As has been previously indicated, the apparent specific weight of the materials in the upper part of compartment 1 is distinctly lower than the apparent specific weight of the materials in compartment 2. Consequently, in order to balance the two columns of materials, a diterence in the heights thereof is required. Weirs D1 and D2 should therefore be set at the levels h1 and h2, respectively, in order to provide such balance. It has also been indicated that it is important to set the weirs to the proper levels h1 and h2 if the apparatus is to perform its operations satisfactorily and in accordance with the purposes of this invention. It might here be pointed out for the sake of clearness, that if the diiTer.- ence between the wei-r height settings -is too great, the apparent weight per unit cross-sectional area of the mate- 'rials in compartment 1 (assuming that the Weir D1 were set too high) would be higher than in compartment 2, with the result that larger quantities of the heavy grains M1 would be transferred from the lower part of compartment 1 to compartment 2 through the opening 5 at the foot of the partition 3, thereby causing the intermediate sorting Zone to take a lower position. If the intermediate zone should move down to the extent that it reaches the vicinity of the passage 5 at the foot of partition 3 the light particles M2 as well as the heavy particles M1, would iind their way .through the passage 5 and into compartment 2, and incorrect sorting will result.

On the other hand, if the difference in the weir height setting is too small, the apparent weight per unit crosssectional area in compartment 1 (assuming that the weir D1 were set too low) would be lower than in the compartment 2, so that fewer of the heavy grains M1 would be transferred from the lower part of compartment 1 into compartment 2, with the result that the intermediate sorting zone would take a higher position in compartment 1. rl`hus, whenever the intermediate zone moved into the vicinity of weir D1 of compartment 1, the heavy particles M1 in such zone would discharge over such Weir with the light particles M2, resulting in a faulty sorting process.

if such difference in the weir height setting was reduced to the extent that the weirs were set roughly at the same level so that the surfaces of the tluidized materials in both compartments are at the same level, the apparent weight per unit cross-sectional area of the materials in compartment 2 would be higher than the apparent weight per unit cross-sectional area of the materials in compartment 1, so that the two columns would be unbalanced. This unbalanced condition Would cause the level of the materials in compartment 2 to fall, ow over the Weir D2 of compartment 2 would cease, .and the apparatus would discharge the solid particle mixture fed into compartment 1 in its original state over the weir D1 of the latter, with the result that no sorting would take place.

The foregoing shows that in the practice of the invention it is critical that the spilling levels of the two compartments be specifically determined .and be such that their difference corresponds to a state of equilibrium between the apparent weights per unit cross-sectional area of the materials in the two columns and, of course,

fto a suitable position of the intermediate sorting zone between the lower edge of the separating partition 3 and the weir D1 of compartment 1. These levels can vary slightly under actual operating conditions from predetermined values, but such variations should not be excessive because then the operation of the apparatus will be adversely affected in the manner above pointed out. When the levels have been properly set, the intermediate sorting zone in column 1 will be automatically maintained in a stable position, irrespective of the proportions of heavy or light materials fed to the apparatus, so that the latter will operate continuously without requiring any special supervision.

In order to facilitate the initial adjustment of the apparatus, the two compartments may be provided with weirs that are adjustable for height. If the adjustable weirs are properly constructed they can also provide a means for adjustment of the apparatus when in operation, should the properties of the materials undergoing sorting vary under fluidization conditions. The weirs may also be replaced by discharge pipes, one for each compartment. The pipes may be provided with means for adjusting theirV head losses and their intakes set at a certain height above the probable material levels. By increasing or reducing the head losses in these pipes, the levels in the respective columns can be raised or lowered as required in order to balance the apparent weights per unit cross-sectional area in the two columns.

1n order to facilitate the understanding of the operation of the apparatus of this invention, the characteristics of a unit designed in accordance wherewith are now given by way of example. Let it be assumed that this particular unit is to sort by density a mixture consisting of one ingredient having a specific gravity of 2.65 and a mean grain size of 180e, and a second ingredient having a specic gravity of 4.25 and a mean grain size of g. As the minimum luidization velocity for the heavy ingredient is 0.05 cm./sec., a velocity of the order of 0.1 cm./sec. will be assumed for the two compartments 1 and 2 in order to ensure uninterrupted tluidization. Under these conditions, and taking the mean level of the intermediate sorting zone as being 34 cm. above the screen 4, the apparatus will operate in accordance with the invention if the Weir height settings are 111:68 cm. in compartment 1 and 112:49 cm. in compartment 2.

By reason of the fact that the apparatus of this invention makes it possible to continuously extract solid materials, such apparatus is .also suitable for use in other processing operations in which sizing is not the main 7 object, such as in the leaching of crushed sylvinite ore under uidized conditions with salt water (NaCl). VIn the employment of the apparatus for such purpose, the fine particles which rapidly give up their potassium chloride content, are discharged via the upper Weir, whereas the coarse particles which are slower to leach, are discharged over the lower Weir after having traveled a longer distance through the .apparatus and thereby having been retained in contact with theV processing liquid for a longer period of time than the liner particles.

Vvhile I have hereinabove described and illustrated in the accompanying drawings by way of example, one embodiment by which my invention may be practiced, it will be apparent to those skilled in the art that other embodiments thereof are possible without departing from the Vspirit of the invention, or the scope of the appended claims.

I claim:

l. A process for sorting a solid particle mixture in a iluidized medium, which comprises feeding the sorting huid 'against an equal head of such fluid up into two upright compartments communicating with each other at their lower ends and at a ow velocity such as to produce in both compartments a permanent uidized state enabling relative movement to occur between the solid particles as will cause their classification from said mixture, feeding the solid particle mixture into the uid ow in one of such compartments at a place intermediate the lower Vand upper ends of lthe uidized column in such compartment, so that there is established in the region of such place a particle sorting zone from which sorted particles of light apparent density can rise in such one compartment and sorted particles of heavy apparent density can fall to the 4bottom of such compartment, maintaining the upper surfaces of the tluidized columns in the compartments at such levels lthat the apparent weight per unit cross-sectional area of the fluidized materials is the same in both compartments, maintaining those sorted particles of heavy apparent density which travel fromthe bottom of such one-compartment into the lower end of the other compartment, isolated from the iluidized material in said one compartment during the rise of such heavy particles in such other compartment and the discharge therefrom, and removing from each of said compartments the sorted solid particles.

2. A process for sorting a solid particle mixture in a fluidized medium, which comprises feeding a sorting liquid against an equal head of such liquid up into two upright compartments communicating with each other at their lower ends and at a llow velocity such as to produce in both compartments a permanent fluidized state enabling relative movement to occur between the solid particles as will cause their classification from said mixture, feeding the solid particle mixture into the liquid llow of one of such compartments at a place located between the lower and upper ends of the uidized column in such compartment, so that there is established in the region of such place a particle sorting zone from which sorted particles of light apparent density can rise in such one compartment and sorted particles of heavy apparent density can fall to the bottom of such compartment, maintaining the iluidized materials in one compartment at a higher level than the uidized materials in the other compartment and with the dilerence between the two levels such that the apparent weight per unit cross-sectional area of the liuidized materials is the same in both compartments, maintaining those sorted particles of heavy apparent density which travel from the bottom of such one compartment into the lower end of the other compartment, isolated from the uidized material in said one compartment during the rise of such heavyrparticles in such other compartment and the discharge therefrom, `and removing from the upper end of the lluidized column in each compartment the sorted solid particles carried thereto by the sorting liquid.

8 3. A process 'for sorting .afsolid particle mixture in a uidized medium such as defined in claim 2, in which both of said compartments extend upwardly in adjacent relation and have a common entry end equal in area to the combined cross-sectional areas of said compartments, and in which a-'liquid flow of cross-sectional area approximating the area of said common entry end is applied to such end.

4. A vprocess for sorting a solid particle mixture in a iuidized medium such .as defined in claim 2, in which the llow velocity of the liquid at its entry into the two --compartments -is practically equal to the velocity of lluidization of the heavy particles in the mixture.

`tluidized materials in the other compartment.

r.7. Av process for sorting a solid particle mixture in a fluidi'zed medium such as defined in claim 2, in which the sorting lluidis fed continuously to both compartments and in which the solid particle mixture is fed continuously to that compartment "in which the iluidized materials are at a higher level than the uidized materialsfin the other compartment.

l 8. A process for sorting a solid particle mixture inra tiuidized medium such as defnedfin claim 2, in which the levels of the columns of uidized materials in the compartments are maintained by the automatic removal of liquid-and sorted solid particles from the vtops of the columns of suchfluidizedrmaterials.

9. A process for'sorting a solid particle mixture in a uidized medium, which comprises feeding a sorting liquid against a head of such liquid up into an upright compartment `provided at its upper end with a Weir over which Vliquid is automatically discharged, feeding `the solid Aparticle mixture linto the yflow of liquid in such compartment yat a place located between and in spaced relation to the ends of the upright compartment, yfeeding said sorting liquid at a lflow velocity such as to enable relative movement to occur between the particles in the mixture and such as will cause the classicationof such particles from the mixture, the rise of the lighter sorted particles toward the weir for discharge thereover, and the fall of the heavy sorted particles Kto the bottom of said compartment, and feeding said ysorting fluid at substantially the same flow velocity and against an equal head'of such fluid upinto a second upright compartment whch is in communication at its lower end with the lower end of said lirst mentioned compartment so that the heavy particles depositing in the latter are drawn into saidsecond compartment, and which is provided at its upper end with a weir over which are discharged the heavier particles that are'advanced through said second compartment by the sorting liquid, and maintaining those sorted particles vof 'heavy apparent density which travel from the bottom of such one compartment into the lower end of the other compartment, isolated from the tluidized material in said one compartment during the rise of such heavy particles in such other compartment and the dischargetherefrom.

l0. A process for sorting a solid particle mixture in a luidized medium such as defined in claim 9, in which the tirst mentioned Weir is at a higher level than the second mentioned weir by a distance such that the apparent weights per unit cross-sectional area Vof the uidized materials in the two compartments are balanced.

ll. An apparatus for sorting a solid particle mixture in a uidized medium, comprising means forming two adjacent upright compartments in communication with each other at the lower ends thereof, means for maintaining an equal head of liquid in said compartments, means for feeding sorting fluid up through one of said compartments at a given flow velocity such as to produce in such compartment a permanent fiuidized state enabling relative movement to occur between the solid particles as will cause their classication from said mixture, means connected to said one compartment for feeding the solid particle mixture into the uid ow therethrough so that there is established a particle sorting zone at a place intermediate the lower and upper ends of the tluidized column in such one compartment, from which zone light particles sorted out of the mixture therein are enabled to rise in the fluidized column and heavy particles sorted out of the mixture in such zone are enabled to move downwardly to the bottom of said one column, said uid feeding means being constructed and arranged to feed the fluid simultaneously up through the other of said compartments so that the heavy particles deposited in said one compartment are drawn into and caused to rise in said other compartment, means for isolating such heavy particles from the fluidized material in said one compartment during the rise of such heavy particles in said other compartment and the discharge therefrom, means for maintaining the upper surfaces of the iluidized columns in the two columns at such levels that the apparent weight per unit cross-sectional area of the uidized materials is the same in both compartments, and means for discharging from the apparatus the sorted particles advanced upwardly in said compartments.

12. Apparatus such as defined in claim 1l, in which said compartment forming means are constituted of two tubular members concentrically arranged one within the other so that the inner tubular member forms a partition between the two compartments.

13. Apparatus such as delined in claim l2, in which said inner tubular member is supported in depending relation in the apparatus with its bottom end raised above the lower end of the outer tubular member to provide an 1G opening between the compartments formed by said members.

14. Apparatus such as dened in claim 1l, in which said compartment forming means provides for said compartments a common entry end equal in area to the combined cross-sectional areas of said compartments, and in which said uid feeding means includes a discharge opening disposed in opposed relation to said common entry end and having an area approximating the area of said common entry end.

15. Apparatus such as dened in claim 11, in which said level maintaining means are operable to maintain the column of lluidized materials in said one compartment at a higher level than the column of uidized materials in the other compartment.

16. Apparatus such as dened in claim 15, in which said level maintaining means are constituted of weirs provided at the places for discharge of the sorted particles from said compartments.

17. Apparatus such as defined in claim 11, in which said compartment forming means are composed of two tubular members concentrically arranged one within the other, the outer of said tubular members extend-ing upwardly to a higher level than the inner tubular member, a housing mounted on said outer tubular member and forming a uid chamber above the latter, a third tubular member connected to the upper end of said inner tubular member and extending upwardly through the upper end of said outer tubular member and into the chamber formed by said housing, and in which said means for maintaining an equal head of liquid in said compartments comprises a Weir provided on said housing at the upper end of the chamber therein and operable to maintain a constant level of fluid in the apparatus.

References Cited in the le of this patent UNITED STATES PATENTS 2,586,818 Harms lFeb. 26, 1952 

1. A PROCESS FOR SORTING A SOLID PARTICLE MIXTURE IN A FLUIDIZED MEDIUM, WHICH COMPRISES FEEDING THE SORTING FLUID AGAINST AN EQUAL HEAD OF SUCH FLUID UP INTO TWO UPRIGHT COMPARTMENTS COMMUNICATING WITH EACH OTHER AT THEIR LOWER ENDS AND AT A FLOW VELOCITY SUCH AS TO PRODUCE IN BOTH COMPARTMENTS A PERMANENT FLUIDIZED STATE ENABLING RELATIVE MOVEMENT TO OCCUR BETWEEN THE SOLID PARTICLES AS WILL CAUSE THEIR CLASSIFICATION FROM SAID MIXTURE, FEEDING THE SOLID PARTICLE MIXTURE INTO THE FLUID FLOW IN ONE OF SUCH COMPARTMENTS AT A PLACE INTERMEDIATE THE LOWER AND UPPER ENDS OF THE FLUIDIZED COLUMN IN SUCH COMPARTMENT, SO THAT THERE IS ESTABLISHED IN THE REGION OF SUCH PLACE A PARTICLE SORTING ZONE FROM WHICH SORTED PARTICLES OF LIGHT APPARENT DENSITY CAN RISE IN SUCH ONE COMPARTMENT AND SORTED PARTICLES OF HEAVY APPARENT DENSITY CAN FALL TO THE BOTTOM OF SUCH COMPARTMENT, MAINTAINING THE UPPER SURFACES OF THE FLUIDIZED COLUMNS IN THE COMPARTMENTS AT SUCH LEVELS THAT THE APPARENT WEIGHT PER UNIT CROSS-SECTIONAL AREA OF THE FLUIDIZED MATERIALS IS THE SAME IN BOTH COMPARTMENTS, MAINTAINING THOSE SORTED PARTICLES OF HEAVY APPARENT DENSITY WHICH TRAVEL FROM THE BOTTOM OF SUCH ONE COMPARTMENT INTO THE LOWER END OF THE OTHER COMPARTMENT, ISOLATED FROM THE FLUIDIZED MATERIAL IN SAID ONE COMPARTMENT DURING THE RISE OF SUCH HEAVY PARTICLES IN SUCH OTHER COMPARTMENT AND THE DISCHARGE THEREFROM, AND REMOVING FROM EACH OF SAID COMPARTMENTS THE SORTED SOLID PARTICLES. 